Cannot Download Asset in Unity 4.6.1f(free Asset)! Need Help..

Hai there, Master and Member of Unity. I have problem here. i have search in this forum n google, but i cann't find any solution for my problem. this my problem.(i Use Unity 4.6.1f): When i want to download asset eg. i want to download asset from survival shooter tutorial , Unity give me error like this:

][1]

****Peer certificate cannot be authenticated with known CA certificates url: https://kharma.unity3d.com/****

i Was trying some solution but it's not work for me and not fixed my problem!

1. setting Proxy

2. setting in Smart security eset

3. change bit chain from 01 to 00

Please help me, who have problem like this that solved. I very appreciated anyone who help me solved my problem..thanks :)